The actuating force for a gear change mechanism of a bicycle hub is usually transmitted from an actuator device fastened to the handle bar of the bicycle to the gear change mechanism by a pulling cable such as a Bowden wire. On the other hand, gear change mechanisms in bicycles are known in which the gear change is effected by a push rod accommodated by an axial bore of the hub axle.
In case of a combination of such a cable transmission and such a push rod actuated gear change mechanism it is necessary to provide at an end portion of the hub axle an actuating force transmission unit which transforms the pull movement of the cable into a push movement of the push rod.
The actuating force transmission unit must be releasably mounted on the respective end portion of the hub axle such that, on the one hand, the actuating force transmission unit takes a well defined axial position along the axis of the hub axle and, on the other hand, the orientation of the actuating force transmission unit is adapted to the path of the respective cable. Moreover, the actuating force transmission unit is not allowed to become loosened during a long period of use of the respective bicycle.